Microprocessor controlled liquid chemical delivery system and method

Abstract

A liquid chemical delivery system automatically delivers viscous chemicals to a number of destinations, such as a number of industrial clothes washers. Several distinct chemicals are pumped, one at a time, into a manifold. The chemical being pumped is mixed with water in the manifold and then transported through a distribution line to its specified destination. By mixing the chemicals with water, viscous chemicals are diluted and delivered using a low pressure delivery system. A single flow meter is used to calibrate all the chemical metering pumps and to recalibrate those pumps periodically, thereby providing accurate chemical metering. The manifold and distribution tube are automatically flushed with water after every chemical delivery so as to reduce corrosion and maintenance costs. In addition, potentially reactive chemicals are kept separate from one another despite the use of only a single distribution line. The system uses a proof-of-flow conductivity meter in the manifold to confirm the presence of each specified chemical in the manifold during the chemical pumping process. Local proof-of-delivery conductivity meters at the system's output ports are used to verify delivery of each chemical to the specified output port.

What is claimed is: 
     
       1. A liquid chemical delivery system comprising: a liquid distribution line having a plurality of output ports;   a plurality of valve means coupled to said liquid distribution line at said output ports, each valve means having a feed position for directing liquid in said distribution line to the corresponding output port and a bypass position for allowing liquid in said distribution line to bypass said corresponding output port;   a manifold coupled to said distribution line;   a plurality of pump means coupled to said manifold, each pump means including means for pumping a corresponding chemical into said manifold;   control means, coupled to said plurality of pump means and said plurality of valve means, for controlling the positions of each said valve means and for enabling specified ones of said pump means, thereby delivering specified chemicals to specified ones of said output ports;   proof of flow conductivity sensing means, coupled to said control means, for detecting the presence of chemicals in said manifold; and   a plurality of proof of delivery conductivity sensing means, coupled to said control means, each said proof of delivery conductivity sensing means located at one of said output ports for detecting delivery of chemicals to said output port;   said control means monitoring said proof of flow conductivity sensing means to verify that specified chemicals are dispensed into said manifold and to determine how long it takes to dispense said specified chemicals; said control means also monitoring said plurality of proof of delivery conductivity sensing means to verify passage of each specified chemical through a specified one of said valve means for a period of time corresponding to how long it took to dispense.   
     
     
       2. The liquid chemical delivery system set forth in claim 1, said control means comparing the amount of time that a specified chemical is pumped into said manifold with the amount of time that said chemical flows through one of said output ports, and confirming delivery of a specified chemical when the difference between said amounts of time does not exceed a predefined error margin. 
     
     
       3. The liquid chemical delivery system set forth in claim 1, further including means for pumping water through said manifold and distribution line after each time that one of said pump means pumps a chemical through said distribution line, thereby flushing said manifold and distribution line with water and separating the chemicals pumped through said distribution line with water;   said control means including means for reversing one of said pump means after said pump means has dispensed a corresponding chemical into said manifold and after said manifold has been subsequently flushed with water; thereby drawing water into said pump means;   whereby said pump means is exposed to said chemical only while dispensing said chemical, reducing chemical attack on said pump means.   
     
     
       4. A liquid chemical delivery system comprising: a manifold for mixing chemical solutions;   a plurality of chemical pumps coupled to said manifold, each chemical pump having means for pumping a corresponding chemical into said manifold;   a liquid distribution line coupled to said manifold having a plurality of output ports;   a plurality of valve means, coupled to said liquid distribution line at said output ports, for diverting liquid flowing through said distribution line into the corresponding output port;   control means, coupled to said plurality of pump means and said plurality of valve means, for controlling each said valve means and for enabling specified ones of said pump means, thereby delivering specified chemicals to specified ones of said output ports; and   a plurality of proof of delivery means, coupled to said control means, each said proof of delivery means located at one of said output ports for detecting delivery of chemicals to said output port;   said control means monitoring how long it takes to dispense each said specified chemical into said manifold and how long it takes said specified chemical to flow through one of said proof of delivery means; said control means comparing the amount of time that a specified chemical is pumped into said manifold with the amount of time that said chemical flows through one of said output ports; said control means confirming delivery of a specified chemical when the difference between said amounts of time does not exceed a predefined error margin.   
     
     
       5. The liquid chemical delivery system set forth in claim 4, further including: proof of flow means, coupled to said control means, for determining when a chemical is present in said manifold; and   autopriming means, coupled to said proof of flow means, for priming any specified one of said chemical pumps by activating with specified chemical pump until said proof of flow means verifies the presence of a chemical in said manifold means.   
     
     
       6. The liquid chemical delivery system set forth in claim 4, further including: water supply means for supplying water to said manifold; and   transport pump means for pumping water through said manifold and said distribution line after each time that a chemical is pumped into said manifold, thereby flushing said manifold and distribution line with water and separating the pumped chemicals with water;   said control means including means for reversing one of said pump means after said pump means has dispensed a corresponding chemical into said manifold and after said manifold has been subsequently flushed with water by said transport pump means; thereby drawing water into said pump means;   whereby said pump means is exposed to said chemical only while dispensing said chemical, reducing chemical attack on said pump means.   
     
     
       7. A method of delivering liquid chemicals, the steps of comprising: providing a manifold, a plurality of chemical pumps for pumping corresponding chemicals into said manifold, a liquid distribution line coupled to said manifold having a plurality of output ports, and a diversion valve at each of said output ports for diverting liquid flowing through said liquid distribution line into the corresponding output port;   enabling a selected one of said chemical pumps and a selected one of said valves so as to deliver a specified chemical to a specified one of said output ports; and   monitoring the conductivity of liquid flowing through said selected output ports so as to verify the delivery of said selected chemical to said selected output port;   monitoring how long it takes to dispense each said selected chemical into said manifold and how long it takes said selected chemical to flow through said selected one of said output ports, comparing the amount of time that said selected chemical is pumped into said manifold with the amount of time that said selected chemical flows through one of said output ports; said control means confirming delivery of a selected chemical when the difference between said amounts of time does not exceed a predefined error margin.   
     
     
       8. The liquid chemical delivery method set forth in claim 7, further including the step of: autopriming any specified one of said chemical pumps by enabling said specified chemical pump and monitoring the conductivity of liquid in said manifold until the presence of a chemical in said manifold means is detected.   
     
     
       9. The liquid chemical delivery method set forth in claim 7, further including the steps of: pumping water through said manifold and said liquid distribution line after each time that a chemical is pumped into said manifold, thereby flushing said manifold and liquid distribution line with water and separating the pumped chemicals with water;   reversing one of said chemical pumps after said chemical pump has dispensed a corresponding chemical into said manifold and after said manifold has been subsequently flushed with water, thereby drawing water into said pump means;   whereby said chemical pump is exposed to said chemical only while dispensing said chemical, reducing chemical attack on said chemical pump.   
     
     
       10. A method of delivering liquid chemicals, the steps of comprising: providing a manifold, a plurality of chemical pumps for pumping corresponding chemicals into said manifold, a liquid distribution line coupled to said manifold having a plurality of output ports, and a diversion valve at each of said output ports for diverting liquid flowing through said liquid distribution line into the corresponding output port;   enabling a selected one of said chemical pumps and a selected one of said valves so as to deliver a specified chemical to a specified one of said output ports;   pumping water through said manifold and said liquid distribution line after each time that a chemical is pumped into said manifold, thereby flushing said manifold and liquid distribution line with water and separating the pumped chemicals with water; and   reversing one of said chemical pumps after said chemical pump has dispensed a corresponding chemical into said manifold and after said manifold has been subsequently flushed with water, thereby drawing water into said pump means;   whereby said one of said chemical pumps is exposed to said chemical only while dispensing said chemical, reducing chemical attack on said one of said chemical pumps.   
     
     
       11. A method of delivering liquid chemicals, the steps of comprising: providing a manifold, a plurality of chemical pumps for pumping corresponding chemicals into said manifold, a liquid distribution line coupled to said manifold having a plurality of output ports, and a diversion valve at each of said output ports for diverting liquid flowing through said liquid distribution line into the corresponding output port;   enabling a selected one of said chemical pumps and a selected one of said valves so as to deliver a specified chemical to a specified one of said output ports; and   supplying water to said manifold as said selected chemical pump pumps a corresponding chemical into said manifold so as to produce a diluted chemical mixture;   measuring the amount of water supplied to said manifold;   measuring the amount of diluted chemical mixture exiting said manifold into said distribution line; and   continuously, while dispensing a specified chemical, computing the difference between the amount of said chemical mixture exiting said manifold and the amount of water supplied to said manifold, and shutting off said selected chemical pump when said difference is equal to a specified amount;   whereby said specified amount of said specified chemical is metered and delivered to a selected output port.   
     
     
       12. The method of delivering liquid chemicals of claim 11, wherein both of said measuring steps are performed using a flow meter which is upstream of the point at which chemicals are pumped by said chemical pumps into said manifold; whereby the amount of chemical dispensed is measured without exposing the flow meter to said chemical. 
     
     
       13. A liquid chemical delivery system comprising: a manifold for mixing chemical solutions;   a plurality of chemical pumps coupled to said manifold, each chemical pump having means for pumping a corresponding chemical into said manifold;   a liquid distribution line coupled to said manifold,   transport pump means, coupling said manifold to said distribution line, for pumping liquid in said manifold into said distribution line;   water supply means coupled to said manifold for supplying water to said manifold; said water supply means including water metering means for measuring the amount of water supplied to said manifold; and   a controller coupled to said chemical pumps, to said transport pump means and to said water metering means, said controller including means for enabling a selected chemical pump so as to pump a corresponding specified chemical into said manifold;   means for determining the amount of water supplied by said water supply means to said manifold;   means for determining the amount of diluted chemical mixture pumped by said transport pump from said manifold into said distribution line; and   means for substantially continuously, while dispensing a specified chemical, computing the difference between the amount of said chemical mixture pumped into said distribution line and the amount of water supplied to said manifold, and shutting off said selected chemical pump when said difference is equal to a specified amount;     whereby said specified amount of said specified chemical is metered and delivered to a selected output port.   
     
     
       14. The method of delivering liquid chemicals of claim 13, wherein both of said means for determining an amount include a flow meter which is located upstream of the point at which chemicals are pumped by said chemical pumps into said manifold; whereby the amount of chemical dispensed is measured without exposing the flow meter to said chemical. 
     
     
       15. The liquid chemical delivery system set forth in claim 13, further including proof of flow conductivity sensing means, coupled to said control means, for detecting the presence of chemicals in said manifold; and   a plurality of proof of delivery conductivity sensing means, coupled to said control means, each said proof of delivery conductivity sensing means located at one of said output ports for detecting delivery of chemicals to said output port;   said control means monitoring said proof of flow conductivity sensing means to verify that specified chemicals are dispensed into said manifold and to determine how long it takes to dispense said specified chemicals; said control means also monitoring said plurality of proof of delivery conductivity sensing means to verify passage of each specified chemical through a specified one of said valve means for a period of time corresponding to how long it took to dispense.   
     
     
       16. The liquid chemical delivery system set forth in claim 15, said controller including means for enabling said transport pump to pump water from said water supply means through said manifold and distribution line after each time that one of said chemical pumps pumps a chemical into said manifold, thereby flushing said manifold and distribution line with water;   said controller reversing said one of said chemical pumps after said chemical pump has been shut off and said manifold has been subsequently flushed with water; thereby drawing water into said one of said chemical pumps;   whereby said one of said chemical pumps is exposed to said corresponding chemical only while dispensing said chemical, reducing chemical attack on said chemical pump.   
     
     
       17. The liquid chemical delivery system set forth in claim 13, said controller including means for enabling said transport pump to pump water from said water supply means through said manifold and distribution line after each time that one of said chemical pumps pumps a chemical into said manifold, thereby flushing said manifold and distribution line with water;   said controller reversing said one of said chemical pumps after said chemical pump has been shut off and said manifold has been subsequently flushed with water; thereby drawing water into said one of said chemical pumps;   whereby said one of said chemical pumps is exposed to said corresponding chemical only while dispensing said chemical, reducing chemical attack on said chemical pump.